Pigments treated with organo-phosphoric acids and their salts

ABSTRACT

A unique treatment for pigments is provided. This treatment, which uses certain organo-phosphoric acids and/or their salts, imparts improved physical and chemical qualities including lacing resistance, improved dispersion and decreased chemical reactivity when these treated pigments are incorporated into polymeric matrices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 09/994,979, filed on Nov. 26, 2001, now U.S. Pat.No. 6,713,543 which is a continuation-in-part application of U.S. patentapplication Ser. No. 09/723,098, filed on Nov. 27, 2000 now U.S. Pat.No. 6,765,041. The present application claims the benefit of the filingdates of the aforementioned applications and incorporates theirdisclosures by reference as if set forth fully herein.

BACKGROUND OF THE INVENTION

The present invention relates to novel pigments, and in particular,pigments that have been treated with certain organo-phosphoric acidcompounds and/or their salts.

The incorporation of pigments into polymer matrices has been performedfor many years, and over the years, pigments have been and continue tobe incorporated into polymer matrices for many reasons. For example,pigments may be used as fillers. They may also be used to impart betterphysical and chemical attributes to polymer matrices, including improvedthermal stability, especially lacing resistance in extruded polymer filmapplications, and decreased chemical activity. In order to obtaindifferent benefits, pigments may be treated in different ways, includingby adding surface treatments.

Commonly used pigments include titanium dioxide, kaolin and calciumcarbonate. Commonly known surface treatments that have been applied topigments include silanes, alkylphosphonic acids and phosphorylatedpolyenes.

The precise attributes that one wants in a treated pigment will dependin part on the application in which it will be used. Often one wants toprovide a hydrophobic pigment that is stable, easy to prepare, costeffective, can be dispersed to a high degree in polymers, and does notreact in the presence of other additives such as lithopone. However,despite the numerous known surface treatments, for various reasons,including cost and desired properties, no known surface treatments areideal for all applications. Thus, there is always a need to develop newand better treatments for pigments.

One under-explored option for treating pigments is the use oforgano-phosphoric acids, including the esters of phosphoric acids andtheir corresponding salts. These compounds have been suggested as usefulwhen mixed in relatively large amounts with pigments and to formsuspensions in, for example, aqueous coatings applications. However,such a use produces a unique product that may be used only in a limitedapplication. Thus, the teachings for the use of relatively large amountsof esters of phosphoric acids in aqueous coatings applications do notsuggest the treatment of pigments with low levels of theorgano-phosphoric acids of this invention or that the pigments treatedwith the low levels of the organo-phosphoric acids of this inventionwould have utility in plastics.

The present invention provides economical and easily prepared novelpigments that possess resistance to lacing when incorporated intopolymeric articles (such as films), do not produce objectionable sidereactions when mixed with common plastics additives such as lithopone,which contains zinc sulfide, and are stable such that they possess lowlevels of extractable organics. Further, durable plastics products thatincorporate the treated pigments of the present invention are likely toresist yellowing when phenolic-type antioxidants are used.

SUMMARY OF THE INVENTION

The present invention provides novel treated pigments for use in polymermatrices. According to the present invention, pigmentary bases aretreated with one or more organo-phosphoric acid compounds and/or theirsalts in order to form treated pigments.

In one embodiment, the treated pigment comprises a pigmentary base thatmay be treated with the reaction products of: (1) at least one organicalcohol; and (2) P₂O₅ and/or phosphoric acid. The phrases “at least oneorganic alcohol” and “organic alcohols” mean one or more types oforganic alcohols, for example, a solution of hexanol or octanol or amixture of hexanol and octanol. The organic alcohols, P₂O₅ andphosphoric acid are selected such that their reaction products includean organo-acid phosphate that may be represented by the formula:(R—O)_(x)PO(OH)_(y)  Formula 1:wherein

-   -   x=1 or 2;    -   y=3−x; and    -   R is an organic group having from 2 to 22 carbon atoms.        Alternatively, one may start with the organo-acid phosphate or        its corresponding salt directly if it is available, rather than        produce it from the reactants described above.

In another embodiment, the present invention provides for a pigmenttreated with an organopyrophosphate or an organopolyphosphate and/ortheir corresponding salts. The organopyrophosphate andorganopolyphosphate compounds may be represented by the formula:R′_(n)—P_((n−2))O_(4+[3(n−3)])  Formula 2:wherein

-   -   n=4-14; and    -   each R′ is an organic group having from 2 to 22 carbon atoms or        hydrogen and within any one molecule, any two or more R′ groups        may be the same provided that at least one of the R′groups is        not hydrogen.

In still another embodiment, the present invention provides for atreated pigment comprised of a pigmentary base that has been treatedwith an organometaphosphate compound and/or its corresponding saltwherein the organometaphosphate compound may be represented by theformula:(R″PO₃)_(m)  Formula 3:wherein

-   -   m=1-14, and each R″ is an organic group having from 2 to 22        carbon atoms or hydrogen and within any one molecule, any two or        more R″ groups may be the same provided that at least one of the        R″ groups is not hydrogen.        Collectively, the group of compounds represented by Formulas        1-3, i.e., the organo-acid phosphate, the organopolyphosphate,        the organopyrophosphate and the organometaphosphate are referred        to herein as “organo-phosphoric acids.”

The treated pigments of the present invention may be combined with andreadily dispersed into polymers to form polymer matrices. For example,the pigments of the present invention may be incorporated into a polymermatrix containing up to about 85% of organo-phosphoric acid treatedtitanium dioxide pigment, based on the weight of the polymer matrix tobe produced. The polymer matrix may be an end-product in and of itselfor a product that will be further processed such as in a masterbatch,which can be let down into a polymeric film. These polymer matrices haveimproved physical properties such as impact strength, tensile strengthand flexural characteristics.

The treated pigments of the present invention may also be used toprepare highly loaded polymer masterbatches. These highly loadedmasterbatches are especially useful in applications in which dispersionand thermal stability, especially resistance to lacing, are critical.

The treated pigments of the present invention have the advantages ofbeing pigments that are stable, easy to prepare, cost effective, can bedispersed to a high degree in polymers, and do not react in the presenceof other additives such as lithopone. Such treated pigments may beuseful in the manufacture of plastics and other products.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides novel pigments for use in connection withpolymers and offers several benefits over currently used pigments.According to the present invention, pigmentary bases are treated with anorgano-phosphoric acid that may be an organo-acid phosphate, anorganopyrophosphate, an organopolyphosphate or an organometaphosphate,or a salt of any of the aforementioned compounds. The pigmentary basesmay also be treated with mixtures of any of the aforementioned compoundsand/or their salts. The resulting treated pigments may then be combinedwith polymers to form novel polymer matrices.

The present disclosure is not intended to be a treatise on eitherpigments or the production of polymer matrices. Readers are referred toappropriate, available texts and other materials in the field foradditional and detailed information on any aspect of practicing thisinvention.

Suitable pigmentary bases for use in the present invention includetitanium dioxide, kaolin, talc, mica and calcium carbonate. The phrase“pigmentary base” as used herein refers to the pigment that has not beentreated with an organo-phosphoric acid compound. Preferably, titaniumdioxide is the chosen pigmentary base. When the pigmentary base istitanium dioxide, the titanium dioxide may be either rutile or anatase,both of which may be produced by processes that are well known to thoseskilled in the art. For certain applications, it may be desirable topre-treat the pigmentary base with inorganic oxides or other compoundsprior to the addition of the organo-phosphoric acid compound in order toalter the attributes of the final product or to facilitate production.

Under the first embodiment, one treats the pigmentary base with anorgano-acid phosphate, which may be formed from the reaction of organicalcohols, and P₂O₅ and/or phosphoric acid. The organic alcohols usefulin the present invention may have hydrocarbon groups from about 2 toabout 22 carbon atoms. These hydrocarbons may be linear or branched,substituted or unsubstituted, and saturated or unsaturated. Someexamples of the organic alcohols suitable for use in the presentinvention include, ethanol, propanol, butanol, isobutanol, tertiarybutanol, pentanol, hexanol, heptanol, octanol, isooctanol,2-ethylhexanol, decanol, dodecanol and the like. Preferably, the alcoholis a linear hexanol, a linear octanol, isooctanol or 2-ethylhexanol. Thealcohol may be combined with either or both P₂O₅ and phosphoric acid.The conditions under which to react these materials in order to form theorgano-acid phosphate are generally known or knowable to those skilledin the art.

Rather than beginning with the organic alcohols and P₂O₅ and/orphosphoric acid, one may start directly with the organo-acid phosphateof the below formula:(R—O)_(x)PO(OH)_(y)  Formula 1:wherein

-   -   x=1 or 2;    -   y=3−x; and    -   R is an organic group having from 2 to 22 carbon atoms.        The phrase “organo-acid phosphate” as used herein refers to a        compound that may be represented by Formula 1. In the        organo-acid phosphate of Formula 1, the organic groups may be        linear or branched, substituted or unsubstituted, and saturated        or unsaturated. Preferably R is a linear hexyl- or        octyl-aliphatic group or a branched hexyl- or octyl-aliphatic        group. The use of hexyl-, octyl- or ethylhexyl-aliphatic groups        will result in excellent pigmentary performance.

In a second embodiment, the present invention provides for a treatedpigment that comprises a pigmentary base that has been treated with anorgano-phosphoric acid compound that is either an organopyrophosphate ororganopolyphosphate. These compounds may be represented by the formula:R′_(n)—P_((n−2))O_(4+[3(n−3)])  Formula 2:wherein

-   -   n=4-14; and    -   each R′ is an organic group having from 2 to 22 carbon atoms or        hydrogen and within any one molecule, any two or more R′ groups        may be the same provided that at least one of the R′ groups is        not hydrogen.        The symbol R′ as used in Formula 2 denotes any organic group        that contains from 2 to 22 carbon atoms or hydrogen. Within any        molecule the R′ groups may all be the same moiety or they may be        different moieties. These organic groups may be linear or        branched, substituted or unsubstituted, and saturated or        unsaturated. If the R′ groups are all the same moieties, then        they cannot be hydrogen. Preferably at least one of the R′        groups is hydrogen and at least one of the R′ groups will be        linear hexyl or octyl aliphatic groups or branched hexyl or        octyl aliphatic groups. Examples of organopyrophosphate acid        compounds and organopolyphosphate acid compounds include        caprylpyrophosphate, 2-ethylhexylpyrophosphate,        dihexylpyrophosphate, dihexylammoniumpyrophosphate,        dioctylpyrophosphate, diisooctylpyrophosphate,        dioctyltriethanolaminepyrophosphate,        bis(2-ethylhexyl)pyrophosphate, bis(2-ethylhexyl) sodium        pyrophosphate, tetraethylpyrophosphate, tetrabuytlpyrophosphate,        tetrahexylpyrophosphate, tetraoctylpyrophosphate,        pentahexyltripolyphosphate, pentaoctyltripolyphosphate,        tetrahexyl sodium tripolyphosphate,        tetrahexylammoniumtripolyphosphate, pentahexyl sodium        tetrapolyphosphate, trioctyl sodium tetrapolyphosphate, trioctyl        potassium tetrapolyphosphate, hexabutyltetrapolyphosphate,        hexahexyltetrapolyphosphate and hexaoctyltetrapolyphosphate.

In a third embodiment, the present invention provides for a treatedpigment comprised of a pigmentary based that has been treated with anorganometaphosphate compound wherein the organometaphosphate compoundmay be represented by the formula:(R″PO₃)_(m)  Formula 3:wherein

-   -   m=1-14, and each R″ is an organic group having from 2 to 22        carbon atoms or hydrogen and within any one molecule, any two or        more R″ groups may be the same provided that at least one of the        R″ groups is not hydrogen.        The symbol R″ as used in Formula 3 denotes any organic group        that contains from 2 to 22 carbon atoms or hydrogen. These        organic groups may be linear or branched, substituted or        unsubstituted, and saturated or unsaturated. “m” may be from        about 1 to about 14, and preferably “m” is from about 4 to        about 14. Within any molecule, the R″ groups may all be the same        moiety or they may be different moieties. If the R″ groups are        all the same moieties, then they cannot be hydrogen. Preferably        at least one of the R″ groups will be a linear hexyl or octyl        aliphatic group or a branched hexyl or octyl aliphatic group.        Examples of organometaphosphates include ethylmetaphosphate,        propylmetaphosphate, butylmetaphosphate, hexylmetaphosphate and        octylmetaphosphate.

The organo-phosphoric acids of the present invention may be utilized intheir acidic or salt forms. Examples of salts useful with the presentinvention are the potassium, sodium, ammonium and aluminum salts andsalts formed with alkanolamines such as triethanolamine of thesubstances identified by Formula 1, Formula 2 or Formula 3.

Organo-acid phosphates are available commercially through, for example,Albright & Wilson Americas of Glen Allen, Va. or may be prepared byprocedures known or knowable to those skilled in the art such as thoseprocedures disclosed in U.S. Pat. No. 4,350,645, issued on Sep. 21, 1982to Kurosaki et al., the teachings of which are incorporated by referenceherein. Organopyrophosphates and organopolyphosphates may be purchasedfrom Akzo Nobel or produced according to the procedures that are knownor easily knowable to persons skilled in the art. Organometaphosphatesmay also be produced according to the procedures that are known oreasily knowable to persons skilled in the art. Examples of theseprocedures for synthesizing organopyrophosphates, organopolyphosphatesand organometaphosphates are described in Alder, Howard and Woodstock,Willard Chem, Indus., 1942, 51: 516, which is incorporated by referenceherein.

The aforementioned organo-phosphoric acids, which are the surfacetreatments of the present invention will be used to treat the pigmentarybases and to form treated pigments. The phrase “treated pigment” refersto any pigmentary base that has been surface treated or modified. Thephrase “organo-phosphoric acid treated pigment” refers to a pigmentarybase that has been treated with the reaction products of organicalcohols and P₂O₅ and/or phosphoric acid; an organo-acid phosphate thatmay be represented by the above Formula 1; an organopyrophosphate ororganopolyphosphate of Formula 2; an organometaphosphate of Formula 3;or a mixture or any of the aforementioned substances. Preferably, thelevel of organo-phosphoric acid or corresponding salt that is used totreat the pigmentary base ranges from about 0.01 percent to about 5percent by weight, based on the weight of the pigmentary base; morepreferably from about 0.3 percent to about 2.0 percent; and mostpreferably from about 0.7 percent to about 1.2 percent.

In the organo-phosphoric acid treated pigment, the organo-phosphoricacid may interact with the pigment in a number of manners such asthrough hydrogen bonding and/or covalent attachments such that thesurface treatment resists extraction from the treated pigment. Theorgano-phosphoric acids that are the reaction products of the organicalcohols, and P₂O₅ and/or phosphoric acid are generally mixtures ofmono- and di-substituted esters in combination with orthophosphoricacid.

The process for making an organo-phosphoric acid treated pigment iseasily and flexibly incorporated into existing pigment productionprocesses. Preferably the combining of the pigmentary base and thesurface treatment of the invention will occur at a temperature of fromabout 10° C. to about 270° C. The specific temperature at which thepigmentary base and the surface treatment are combined is dependent onthe step during the pigment production process in which the surfacetreatment is added.

When an organo-phosphoric acid is used to treat a pigment according tothe present invention, a by-product is thought to be water. Becausewater is the by-product, the organo-phosphoric acid may be added at anyone of, or several of, the operations in the pigment production process.For example, the organo-phosphoric acid may be added to a washed filtercake prior to spray drying, to a high intensity milling device or to amicronizer feed prior to or concurrent with micronization. It is not aseffective to add the organo-phosphoric acid to a pigment slurry prior tofiltration and washing since a portion of the organo-phosphoric acidwill be lost upon washing of the pigment depending on the pH. Theorgano-phosphoric acid can be added to a washed filter cake at normalprocess operating temperatures. If the organo-phosphoric acid is a solidsubstance, it may be dissolved in an appropriate solvent, such as water,alcohol, tetrahydrofurn, etc., before being added to the pigmentarybase. It is desirable to add the organo-phosphoric acid to a fluidized,washed filter cake with agitation in order to assure uniform mixing ofthe organo-phosphoric acid among the pigment particles. The pH of thefluidized filter cake prior to addition of the organo-phosphoric acid isnot critical, and normal operating pH values are acceptable. Thesevalues are known or readily knowable to those skilled in the art. If theorgano-phosphoric acid is added to a dry pigment such as a spray drierproduct or micronizer feed, care must be taken to ensure uniform mixingof the organo-phosphoric acid with the pigment powder.

Devices such as a V-shell blender equipped with an intensifier bar forapplication of the liquid organic or other suitable mixing devices knownto those in the art may be used. Alternatively, the organo-phosphoricacid may be metered into the micronizer along with the pigment powder tobe ground. Air or steam micronization techniques may be used attemperatures from room temperature up to 250° C. or higher as is knownor easily knowable to those skilled in the art.

If one adds the organo-phosphoric acid of the present invention to thefilter cake or to the micronizer feed, one will minimize the loss of theorganic portion of the surface treatment and thereby improvemanufacturing efficiency. The treated pigment may be fluid energy milledusing steam or air to produce finished pigments that retain high levelsof the organo-phosphoric acid compound, which would reduce the overallcost of producing the treated pigment.

When, for example, the pigment is titanium dioxide, organo-phosphoricacid may be added to the untreated titanium dioxide obtained from aproduction process such as the chloride or sulfate processes.Alternatively, the pigmentary base titanium dioxide may be furthertreated with additional metal oxides, such as aluminum oxide, silicondioxide, zirconium oxide and the like, using any process known to thoseskilled in the art, prior to treatment with the organo-phosphoric acidof the present invention. Additionally, the untreated pigmentary base orthe treated pigment may be secondarily treated with polyalcohols such astrimethylolethane and trimethylolpropane or alkanolamines such astriethanolamine.

Once the organo-phosphoric acid treated pigment is formed, it may thenbe combined with a polymer. The nature of the surface treatment of thepresent invention allows the treated pigments to be easily incorporatedinto a polymer matrix. The phrase “polymer matrix” refers to thesubstance comprising the polymer and the treated pigment. Polymers thatmay be of use in the present invention include polymers of unsubstitutedethylene monomers, including polyethylene, polypropylene, polybutylene,and copolymers of ethylene with alpha-olefins containing 4 to 12 carbonatoms or vinyl acetate; vinyl homopolymers, acrylic homopolymers andcopolymers, polyamides, polycarbonates, polystyrene,acrylonitrile-butadiene-styrenes and polyethers. Other suitable polymertypes also include polyvinylchloride, polyurethanes, polysulfones,polyimides, polyesters and chlorinated polyesters, polyoxyethylenes,phenolics, alkyds, amino resins, epoxy resins, phenoxy resins and acetalresins.

The treated pigment may be combined with the polymer and have a loadingof up to about 85% by weight, based on the weight of the polymer matrix.Preferably a loading of treated pigment of about 50% to about 85% byweight based on the weight of the polymer matrix is used. This loadingmay be used as a masterbatch. A “masterbatch” is meant to refer to amixture of two or more substances that are blended together and thenblended with one or more other ingredients that may be the same ordifferent as either of the first two substances. The methods forcreating a masterbatch with the treated pigment are known or easilyknowable to those skilled in the art. For example, the masterbatch maybe created by combining the treated pigment and the polymer using a BRBanbury Mixer.

It has been found, surprisingly and unexpectedly, that the treatedpigments of this invention do not generate potentially hazardous ornoxious gases when used in combination with the polymeric fillerlithopone, which contains combinations of zinc sulfide and bariumsulfate. Lithopone, a composition containing zinc sulfide is used as afiller and extender in various polymer compositions. When a TiO₂ pigmenttreated with a phosphorylated polyene is contacted with zinc sulfide attemperatures greater than about 20 to 25° C., noxious odors aregenerated. In contrast, no odors are generated when pigments of thepresent invention are contacted with zinc sulfide under the sameconditions.

It has also been found, surprisingly and unexpectedly that the treatedpigments of this invention impart greater lacing resistance to polymersinto which they are incorporated. Lacing, which is a believed to be ameasure of volatility at specific weight percent pigment loadings andprocessing temperatures, may manifest as a void or hole in a plasticfilm.

EXAMPLES

The following examples set forth preferred embodiments of the invention.These embodiments are merely illustrative and are not intended andshould not be construed to limit the claimed invention in any way. Amongthe parameters described in the examples below are lacing evaluationsand dispersion testing. The methods used to describe these parametersare set forth prior the specific examples.

Lacing Evaluations

The high temperature stability of polymers containing pigments is animportant property of commercial polymer films, especially polyethylenefilm applications. Voiding or “lacing” accompanies the failure of films.Lacing is believed to be a measure of volatility at specific weightpercent pigment loadings and processing temperatures.

For the present invention, lacing tests were conducted on 50% TiO₂concentrate samples prepared using a Haake Rheocord 9000 ComputerControlled Torque Rheometer. Thus, 125 g of TiO₂ and 125 g of LDPE 722manufactured by Dow Chemical Company were dry blended and added to the75° C. preheated chamber with rotors running at 50 rpm. One minute afteraddition of the TiO₂/LDPE mixture, the chamber temperature was raised to105° C. Frictional heat generated by the mixing process was allowed todrive the rate of incorporation of the TiO₂ into the LDPE until a steadystate mixture was achieved. The concentrate was removed from the mixingchamber and placed into a Cumberland Crusher to obtain finely granulated50% concentrate samples. The granulated samples were then pelletized ona Killion 25 mm single screw extruder with a 20:1 L/D ratio, equippedwith a strand die, water bath and pelletizer. A flat temperature profileof 180° C. was used to extrude the masterbatch pellets. The granulatedconcentrates were conditioned for 48 hours at 23° C. and 50% relativehumidity. These concentrates were then let down into Dow Chemical 722LDPE to achieve a 20% loading of TiO₂ in the final film.

Lacing evaluations were run on a 1″ extruder equipped with a cast filmslot die. A temperature profile of 625° F. die, 515° F. clamp ring, 415°F. zone 3, 350° F. zone 2, and 300° F. zone 1 was used. The screw speedwas set at about 90 rpm. A 25.4 cm polished chrome chill roll, set inconjunction with the extruder was used to maintain a 75-μm-filmthickness, and to cool and transport the films. The chill roll distancefrom the die lips was about 22 mm and the temperature was about 27° C.

After the TiO₂/LDPE mix was placed in the hopper, the material wasallowed to purge until the appearance of a white tint in the film wasfirst noted. To ensure the concentration of TiO₂ in the film hadstabilized, a time interval of two minutes was allowed before lacingobservations were recorded and a film sample obtained. The extruder wasthen purged with LDPE until the film turned clear. Lacing performancewas determined by counting the relative size and number of holesgenerated in a film sample laid out on a dark surface. A 1.0-3.0 ratingsystem was used. A rating of 1 was given to films with no lacing, 2 wasgiven, to films showing the onset of lacing and 3 was given to filmswith extreme lacing. Increments of 0.1 were used to give an indicationof the relative performance between the samples.

Dispersion Testing

Using a small-scale laboratory extrusion apparatus, a measure of pigmentdispersion into organic polymers was obtained by measuring the relativeamount of pigment trapped onto screens of extruder screen packs. Testswere made using 75% TiO₂ concentrates in low density polyethyleneprepared using a Haake 3000 Rheomix mixer. The mixer was controlled andmonitored with a Haake 9000 Rheocord Torque Rheometer. 337.7 grams ofmicronized TiO₂ and 112.6 grams of NA209 LDPE manufactured by Equistarwere dry blended and added to the 75° C. mixing chamber with rotorsoperating at 50 rpm. The mixer temperature was programmed to increase to120° C. one minute after the dry blend was introduced to the mixingchamber. After a steady state mixture was achieved, the compound wasmixed for an additional 3 minutes. The compound was removed from thechamber and granulated using a Cumberland crusher.

Dispersion tests were conducted using a Killion single screw extruder,model KL-100 equipped with a 20:1 length to diameter screw. The extruderwas preheated at 330, 350, 390 and 380° F. from zone 1 to the die,respectively, and operated at 70 rpm. A purge of 1000 grams of NA952LDPE manufactured by Equistar was run through the system, and a newscreen pack was installed. The screen pack consisted of 40/500/200/100mesh screens from the die towards the extruder throat. After temperaturestabilization, 133.33 grams of granulated 75% TiO₂ concentrate was fedinto the extruder. This was followed with 1500 grams of NA952 purge asthe feed hopper emptied. After the LDPE purge was extruded, the screenswere removed, separated and tested using a relative count technique fromthe measurements from an X-ray fluorescence spectrometer. The number ofTiO₂ counts per second was obtained for the 100, 200 and 500 meshscreens in the pack and totaled to obtain the dispersion result. A countresult of less than 5000 is considered to represent excellentdispersion.

Example 1 Octyl Acid Phosphate Prepared in Accordance with U.S. Pat. No.4,350,645

To 65.12 g of 1-octanol (0.5 mol) and 9.0 g of water (0.5 mol),phosphorous pentoxide (70.96 g, 0.5 mol) was added gradually withvigorous stirring while maintaining the temperature below 80° C. Thereaction mixture was stirred for 3 hours at 80° C. Subsequently, another65.12 g of 1-octanol (0.5 mol) was added. The mixture continued to stirfor another 10 hours at 80° C. This method is more fully described inU.S. Pat. No. 4,350,645, which is incorporated by reference herein.

The resulting mixture was analyzed via titration methods, following theteachings of International Patent Application Serial NumberPCT/JP95/01891, which is incorporated by reference herein, and found toyield 63-68% mono octyl acid phosphate, ˜21% dioctyl acid phosphate and˜7% phosphoric acid.

Example 2 Hexyl Acid Phosphate

Example 1 was repeated using 1-hexanol in place of the 1-octanol. Thefinal product contains the presence of 60% monohexyl acid phosphate, 18%dihexyl acid phosphate, and ˜12% phosphoric acid.

Example 3 Polymer Matrices From Octyl Acid Phosphate Treated TiO₂(Chloride Process)

51.8 mls of a 386.4 grams Al₂O₃/liter solution of sodium aluminate wereadded to 5000 grams of the TiO₂ in a 350 grams/liter slurry with mixingat 70° C. The pH was adjusted to 7.0 using a 50% sodium hydroxidesolution, and the slurry was allowed to age for 30 minutes.

The aged slurry was filtered and washed three times with 5000 mlaliquots of 80° C. deionized water, and then dried overnight at 115° C.in a drying oven.

The dried filter cake was forced through an 8-mesh sieve prior totreatment with octyl acid phosphate. 8.4 grams of the reaction productof octanol, P₂O₅ and phosphoric acid from Example 1 were added drop-wiseto 1200 grams of the dry, 8 meshed, alumina coated TiO₂, which wasspread to a 1-cm thickness on polyethylene film. The pigment was mixedand transferred to a one gallon wide-mouthed plastic bottle and agitatedfor 10 minutes on a roller mill. The resulting material was steammicronized to produce the finished pigment.

The finished pigment was incorporated into a low-density polyethylene in75% and 50% masterbatches for dispersion and lacing evaluations. Resultsare given in Table 1 below.

Example 4 Polymer Matrices From Octyl Acid Phosphate Treated TiO₂(Sulfate Process)

51.8 ml of a 386.4 grams Al₂O₃/liter solution of sodium aluminate wereadded to 5000 grams of fine particle sulfate process rutile TiO₂ in a350 grams/liter slurry with mixing at 70° C. The slurry pH was adjustedto 7.0 using a 50% sodium hydroxide solution, and the slurry was allowedto age for 30 minutes. The aged slurry was filtered and washed threetimes with 5000 ml aliquots of 80° C. deionized water and driedovernight at 115° C.

The dried filter cake was forced through an 8-mesh sieve in preparationfor treatment with octyl acid phosphate. 8.4 grams of the octyl acidphosphate product were added dropwise from a syringe to 1200 grams ofthe dry, 8 meshed, alumina coated TiO₂ spread to a 1 cm thickness onpolyethylene film. The pigment was mixed and transferred to a one gallonwide-mouthed bottle and agitated for 10 minutes on a roller mill. Theraw pigment was steam micronized to produce the finished pigment.

The finished pigment was incorporated into 75% and 50% TiO₂ basedmasterbatches containing low-density polyethylene for dispersion andlacing evaluations. Results are given in Table 1 below.

Comparative Example 1

Rutile TiO₂, prepared by the chloride process, coated with hydrousalumina as described in Example 3 was treated with 0.60% by weighttriethanolamine based on the weight of dry pigment. The triethanolaminetreated pigment was steam micronized to produce the finished pigment.

The finished pigment was incorporated into 75% and 50% TiO₂ containinglow-density polyethylene masterbatches for dispersion and lacingevaluations. Results are given in Table 1 below.

Comparative Example 2

A sulfate process rutile TiO₂ base was coated with alumina as describedin Example 4. The organic treatment applied to the dry, 8-meshed aluminacoated, sulfate process TiO₂ was 0.60% by weight triethanolamine basedupon the weight of the dry pigment. The triethanolamine treated pigmentwas steam micronized to produce the finished pigment. The finishedpigment was incorporated into 75% and 50% TiO₂ masterbatches fordispersion and lacing evaluations. Results are given in Table 1 below.

TABLE 1 Dispersion (Counts/Second) Lacing Example 3 1,750 1.7 Example 45,140 1.5 Comparative Example 1 13,700 1.4 Comparative Example 2 24,0001.2

The data illustrate that dispersion performance of both chloride andsulfate process-based pigments, treated with the octyl acid phosphatereaction product (Examples 3 and 4), is dramatically improved over likepigmentary bases treated with a conventional, commercially used organictreatment, triethanolamine (comparative Examples 1 and 2). Further, theexcellent dispersion performance is obtained with no significant decayin resistance to lacing. The standard error for the lacing measurementis about 0.1 to 0.2.

Examples 5-21 Dispersion and Lacing

In the following examples (Examples 5-21), the organo-acid phosphate wasadded to a dry, chloride process base rutile TiO₂ further treated with0.20% by weight of alumina, prior to micronization. The organo-acidphosphate ester was added as a neat liquid or in solution if theorgano-acid phosphate was a solid material. The general preparationmethod used for producing the organo-acid phosphate, alumina treatedpigmentary base was as follows:

25.9 mls of a 386.4 grams Al₂O₃/liter solution of sodium aluminate wereadded with mixing to 5000 grams of the TiO₂ in a 350 grams/liter slurryat 70° C. The pH was adjusted to 7.0 using a 50% sodium hydroxidesolution, and the slurry was allowed to age for 30 minutes.

The aged slurry was filtered and washed three times with 5000 mlaliquots of 80° C. deionized water, and then dried overnight at 115° C.in a drying oven. The dried filter cake was forced through an 8-meshsieve prior to treatment with the organo-acid phosphate. The desiredamount of organo-acid phosphate was added dropwise to 1200 grams of thedry, 8 meshed, alumina coated TiO₂, which was spread to a 1-cm thicknesson polyethylene film. If the organo-acid phosphate was a solid material,it was dissolved in tetrahydrofuran (THF) prior to application to thedry pigment, and the THF was allowed to evaporate. The pigment was mixedand transferred to a one gallon wide-mouthed plastic bottle and agitatedfor 10 minutes on a roller mill. The resulting material was steammicronized to produce the finished pigment.

Example 5 0.9% Octyl Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 0.9% octyl acid phosphate prepared according to Example 1and steam micronized to produce the final product. The finished pigmentwas incorporated into low-density polyethylene in 75% and 50%masterbatches for dispersion and lacing evaluations. Dispersion resultswere 780 XRF counts of TiO₂/sec and lacing was rated a 1.5.

Example 6 1.1% Octyl Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 1.1% octyl acid phosphate prepared according to Example 1and steam micronized to produce the final product. The finished pigmentwas incorporated into low-density polyethylene in 75% and 50%masterbatches for dispersion and lacing evaluations. Dispersion resultswere 1,080 XRF counts of TiO₂/sec and lacing was rated 1.3.

Example 7 0.9% Hexyl Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 0.9% hexyl acid phosphate prepared according to the methodof Example 2 and steam micronized to produce the final product. Thefinished pigment was incorporated into low-density polyethylene in 75%and 50% masterbatches for dispersion and lacing evaluations. Dispersionresults were 1,260 XRF counts of TiO₂/sec and lacing was rated 1.3.

Example 8 1.1% Hexyl Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 1.1% hexyl acid phosphate prepared according to the methodof Example 2 and steam micronized to produce the final product. Thefinished pigment was incorporated into low-density polyethylene in 75%and 50% masterbatches for dispersion and lacing evaluations. Dispersionresults were 1,310 XRF counts of TiO₂/sec and lacing was rated 1.2.

Example 9 0.5% Butyl Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 0.5% butyl acid phosphate obtained from Albright and WilsonAmericas and steam micronized to produce the final product. The finishedpigment was incorporated into a 75% by weight low-density polyethylenemasterbatch for dispersion evaluation. The dispersion result was 12,720XRF counts of TiO₂/sec.

Example 10 0.7% Butyl Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 0.7% butyl acid phosphate obtained from Albright and WilsonAmericas and steam micronized to produce the final product. The finishedpigment was incorporated into a 75% by weight low-density polyethylenemasterbatch for dispersion evaluation. The dispersion result was 2,180XRF counts of TiO₂/sec.

Example 11 0.9% Butyl Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 0.9% butyl acid phosphate obtained from Albright and WilsonAmericas and steam micronized to produce the final product. The finishedpigment was incorporated into a 75% by weight low-density polyethylenemasterbatch for dispersion evaluation. The dispersion result was 1,030XRF counts of TiO₂/sec.

Example 12 0.9% 2-Ethylhexyl Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 0.9% 2-ethylhexyl acid phosphate, which was commerciallyavailable from Specialty Industrial Products, Inc. under the tradenameSipophos 2EHP, and steam micronized to produce the final product. Thefinished pigment was incorporated into a 75% by weight low-densitypolyethylene masterbatch for dispersion evaluation. The dispersionresult was 790 XRF counts of TiO₂/sec.

Example 13 1.1% 2-Ethylhexyl Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 1.1% 2-ethylhexyl acid phosphate, which was commerciallyavailable from Specialty Industrial Products, Inc. under the tradenameSipophos 2EHP, and steam micronized to produce the final product. Thefinished pigment was incorporated into a 75% by weight low-densitypolyethylene masterbatch for dispersion evaluation. The dispersionresult was 280 XRF counts of TiO₂/sec.

Example 14 0.9% Cetyl Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 0.9% cetyl acid phosphate, which was commercially availablefrom Colonial Chemical Company under the tradename Colafax CPE, andsteam micronized to produce the final product. The finished pigment wasincorporated into a 75% by weight low-density polyethylene masterbatchfor dispersion evaluation. The dispersion result was 15,140 XRF countsof TiO₂/sec.

Example 15 1.1% Cetyl Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 1.1% cetyl acid phosphate, which was commercially availablefrom Colonial Chemical Company under the tradename Colafax CPE, andsteam micronized to produce the final product. The finished pigment wasincorporated into a 75% by weight low-density polyethylene masterbatchfor dispersion evaluation. The dispersion result was 2,970 XRF counts ofTiO₂/sec.

Example 16 0.7% Oleyl Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 0.7% oleyl acid phosphate, which was commercially availablefrom Albright & Wilson Americas under the tradename DURAPHOS APO-128,and steam micronized to produce the final product. The finished pigmentwas incorporated into a 75% by weight low-density polyethylenemasterbatch for dispersion evaluation. The dispersion result was 25,730XRF counts of TiO₂/sec.

Example 17 0.9% Oleyl Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 0.9% oleyl acid phosphate, which was commercially availablefrom Albright & Wilson Americas under the tradename DURAPHOS APO-128,and steam micronized to produce the final product. The finished pigmentwas incorporated into a 75% by weight low-density polyethylenemasterbatch for dispersion evaluation. The dispersion result was 20,720XRF counts of TiO₂/sec.

Example 18 0.5% Bis(2-ethylhexyl) Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 0.5% bis(2-ethylhexyl) acid phosphate, which wascommercially available from Albright & Wilson Americas, and steammicronized to produce the final product. The finished pigment wasincorporated into a 75% by weight low-density polyethylene masterbatchfor dispersion evaluation. The dispersion result was 5,610 XRF counts ofTiO₂/sec.

Example 19 0.7% Bis(2-ethylhexyl) Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 0.7% bis(2-ethylhexyl) acid phosphate, which wascommercially available from Albright & Wilson Americas, and steammicronized to produce the final product. The finished pigment wasincorporated into a 75% by weight low-density polyethylene masterbatchfor dispersion evaluation. The dispersion result was 1,120 XRF counts ofTiO₂/sec.

Example 20 0.9% Bis(2-ethylhexyl) Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 0.9% bis(2-ethylhexyl) acid phosphate, which wascommercially available from Albright & Wilson Americas, and steammicronized to produce the final product. The finished pigment wasincorporated into a 75% by weight low-density poly/ethylene masterbatchfor dispersion evaluation. The dispersion result was 1,530 XRF counts ofTiO₂/sec.

Example 21 1.1% Bis(2-ethylhexyl) Acid Phosphate Treated TiO₂

The pigmentary base prepared according to the above-described method wastreated with 1.1% bis(2-ethylhexyl) acid phosphate, which wascommercially available from Albright & Wilson Americas, and steammicronized to produce the final product. The finished pigment wasincorporated into a 75% by weight low-density polyethylene masterbatchfor dispersion evaluation. The dispersion result was 1,070 XRF counts ofTiO₂/sec.

Zinc Sulfide Reactivity Example 22 Zinc Sulfide and PhosphorylatedPolyenes

5 grams of a pigment product comprising titanium dioxide and aphosphorylated polyene were placed in a sealed vial with 1 g of zincsulfide. The vial was heated to 195° C. for 10 minutes. Noxious vaporsemanating from the vial were injected in to a Hewlett-Packard GC-MS anddimethyl disulfide and dimethyl trisulfide were detected.

Example 23 Zinc Sulfide and Octyl Acid Phosphate Treated TiO₂

5 grams of the pigment as prepared in Example 3 were placed in a sealedvial with 1 g of zinc sulfide. The vial was heated to 195° C. for 10minutes. No noxious odors were detected nor were sulfur componentsdetected via GC-MS.

Extraction of Finished Pigments

Samples of finished pigments from Examples 3 and 4 were extracted usingSoxhlet extraction procedures with hexane, tetrahydrofuran and a 10%:90%ethanol:water (W/W) mixture as extraction solvents. The carbon contentsof the dried pigments were determined both before and after extraction.Results are shown below in Table 2.

TABLE 2 % Carbon Example 3 Example 4 theoretical 0.31 0.31 beforeextraction 0.28 0.28 after hexane extraction 0.28 0.27 after THFextraction 0.29 0.27 after EtOH: H₂O extraction 0.28 0.25

Based on the extraction results, the organo-acid phosphate is apparentlystrongly bonded to the TiO₂ pigment since carbons levels of the treatedpigment are not significantly affected by extraction. Further, theoctyl-acid phosphate appears not to be appreciably hydrolyzed during thehigh temperature steam micronization process since over 90% of the addedcarbon remains attached to the pigment after micronization. It would beexpected that hydrolysis of the acid phosphate would liberate octanol,which is volatile and would evaporate during micronization.

Example 24 Acid Form of Caprylpyrophosphate

The acid form of caprylpyrophosphate was prepared from its correspondingsodium salt (purchased from Chem Service, Inc. P.O. Box 599, WestChester, Pa., 19381; Catalog # S-481) according to the followingprocedure: A portion of the sodium salt (˜37 gm) was dissolved in waterand acidified with concentrated HCl until pH<2. The resulting reactionmixture was then extracted with 3×200 mL of diethyl ether. The combinedorganic layers were washed with 5×200 mL of water and then dried overanhydrous MgSO₄. The ether layer was decanted, and the remaining dryingagent was washed with 50 mL of diethyl ether, and the ether wasdecanted. The combined ether extracts were evaporated on a rotaryevaporator at room temperature. The remaining residue was used for TiO₂surface treatment.

Example 25 Acid Form of Caprylpyrophosphate

51.8 mls of a 386.4 grams Al₂O₃/liter solution of sodium aluminate wereadded to 5000 grams of oxidizer product TiO₂ in a 350 grams/liter slurrywith mixing at 70° C. The pH was adjusted to 7.0 using a 50% sodiumhydroxide solution, and the slurry was allowed to age for 30 minutes.

The aged slurry was filtered and washed three times with 5000 mlaliquots of 80° C. deionized water, and then dried overnight at 115° C.in a drying oven. The dried filter cake was forced through an 8-meshsieve prior to treatment with caprylpolyphosphate.

10.75 g of the acid form of caprylpyrophosphate prepared according tothe method of example 24 were added drop-wise to 980 grams of the dry, 8meshed, alumina coated TiO₂, which was spread to a 1-cm thickness onpolyethylene film. The pigment was mixed and transferred to a one gallonwide-mouthed plastic bottle and agitated for 10 minutes on a rollermill. The resulting material was steam micronized to produce thefinished pigment.

The finished pigment was incorporated into low-density polyethylene in75% and 50% masterbatches for dispersion and lacing evaluations. Resultsare given Table 3.

Example 26 Acid Form of 2-Ethylhexylpyrophosphate

The acid form of 2-ethylhexyl-pyrophosphate was prepared from itscorresponding sodium salt (purchased from Chem Service, Inc. P.O. Box599, West Chester, Pa., 19381; Catalog # S-480) according to thefollowing procedure: A portion of the sodium salt (˜37 gm) was dissolvedin water and acidified with concentrated HCl until pH<2. The resultingreaction mixture was then extracted with 3×200 mL of diethyl ether. Thecombined organic layers were washed with 5×200 mL of water and thendried over anhydrous MgSO₄. The ether layer was decanted, and theremaining drying agent was washed with 50 mL of diethyl ether, and theether was decanted. The combined ether extracts were evaporated on arotary evaporator at room temperature. The remaining residue was usedfor TiO₂ surface treatment.

Example 27 Acid Form of 2-Ethylhexylpyrophosphate

11.20 grams of the acid form of 2-ethylhexyl-pyrophosphate prepared inexample 26 were added drop-wise to 1000 grams of the dry, 8 meshed,alumina coated TiO₂ prepared according to example 25, which was spreadto a 1-cm thickness on polyethylene film. The pigment was mixed andtransferred to a one gallon wide-mouthed plastic bottle and agitated for10 minutes on a roller mill. The resulting material was steam micronizedto produce the finished pigment.

The finished pigment was incorporated into low-density polyethylene in75% and 50% masterbatches for dispersion and lacing evaluations. Resultsare given in Table 3.

Example 28 Sodium Salt of Caprylpyrophosphate

15.08 grams of the sodium salt of caprylpyrophosphate obtained from ChemService Inc, catalogue # S-481, were dissolved in 30.9 grams ofdeionized water. The aqueous solution was added drop-wise to 1000 gramsof dry, 8 meshed, alumina coated TiO₂ prepared according to example 25,which was spread to a 1-cm thickness on polyethylene film. The pigmentwas mixed and transferred to a one gallon wide-mouthed plastic bottleand agitated for 10 minutes on a roller mill. The resulting material wassteam micronized to produce the finished pigment.

The finished pigment was incorporated into low-density polyethylene in75% and 50% masterbatches for dispersion and lacing evaluations. Resultsare given in the Table 3w.

Example 29 Sodium Salt of Caprylpyrophosphate

18.38 grams of the sodium salt of caprylpyrophosphate obtained from ChemService Inc, catalogue # S-481, were dissolved in 33.1 grams ofdeionized water. The aqueous solution was added drop-wise to 1000 gramsof dry, 8 meshed, alumina coated TiO₂ prepared according to example 25,which was spread to a 1-cm thickness on polyethylene film. The pigmentwas mixed and transferred to a one gallon wide-mouthed plastic bottleand agitated for 10 minutes on a roller mill. The resulting material wassteam micronized to produce the finished pigment.

The finished pigment was incorporated into low-density polyethylene in75% and 50% masterbatches for dispersion and lacing evaluations. Resultsare given in Table 3.

Example 30 Sodium Salt of 2-Ethylhexyl Polyphosphate

15.05 grams of the sodium salt of 2-ethylhexyl polyphosphate obtainedfrom Chem Service Inc, catalogue # S-480, were dissolved in 26.9 gramsof deionized water. The aqueous solution was added drop-wise to 1000grams of dry, 8 meshed, alumina coated TiO₂ prepared according toexample 25, which was spread to a 1-cm thickness on polyethylene film.The pigment was mixed and transferred to a one gallon wide-mouthedplastic bottle and agitated for 10 minutes on a roller mill. Theresulting material was steam micronized to produce the finished pigment.

The finished pigment was incorporated into low-density polyethylene in75% and 50% masterbatches for dispersion and lacing evaluations. Resultsare given in Table 3.

Example 31 Acid Form of Dihexylpyrophosphate

The acid form of dihexylpyrophosphate, acid form was prepared inaccordance to Alder, Howard and Woodstock, Willard. Chem. Industries,1942, 51, 516 with the following considerations: 28.4 grams of P₂O₅ wereadding to 40.8 grams of 1-hexanol with stirring using a stir bar or amechanical stirrer. No cooling was employed during the reaction. Thetemperature reached as high as ˜125-145° C. during the mixing of theP₂O₅ with the alcohol, and the reaction was considered complete when thetemperature declined to room temperature.

10.89 grams of the acid form of dihexylpyrophosphate prepared accordingto the above method were dissolved in 16.6 grams of tetrahydrofuran. Thetetrahydrofuran solution of dihexylpyrophosphate was added drop-wise to1200 grams of dry, 8 meshed, alumina coated TiO₂ prepared according toexample 25, which was spread to a 1-cm thickness on polyethylene film.The pigment was mixed and transferred to a one gallon wide-mouthedplastic bottle and agitated for 10 minutes on a roller mill. Theresulting material was steam micronized to produce the finished pigment.

The finished pigment was incorporated into low-density polyethylene in75% and 50% masterbatches for dispersion and lacing evaluations. Resultsare given in Table 3.

Example 32 Acid Form of Dihexylpyrophosphate

14.52 grams of the acid form of dihexylpyrophosphate prepared accordingto the method described in example 31 were dissolved in 21.7 grams oftetrahydrofuran. The tetrahydrofuran solution of dihexylpyrophosphatewas added drop-wise to 1200 grams of dry, 8 meshed, alumina coated TiO₂prepared according to example 25, which was spread to a 1-cm thicknesson polyethylene film. The pigment was mixed and transferred to a onegallon wide-mouthed plastic bottle and agitated for 10 minutes on aroller mill. The resulting material was steam micronized to produce thefinished pigment.

The finished pigment was incorporated into low-density polyethylene in75% and 50% masterbatches for dispersion and lacing evaluations. Resultsare given in Table 3.

Example 33 Acid Form of Dioctylpyrophosphate

The acid form of dioctylpyrophosphate, was prepared in accordance toAlder, Howard and Woodstock, Willard. Chem. Industries, 1942, 51, 516with the following considerations:

28.4 grams of P₂O₅ were added to 52.0 grams of 1-octanol with stirringusing a stir bar or a mechanical stirrer. No cooling was employed duringthe reaction. The temperature reached as high as ˜125-145° C. during themixing of the P₂O₅ with the alcohol, and the reaction was consideredcomplete when the temperature declined to room temperature.

10.80 grams of the acid form of dioctylpyrophosphate prepared accordingto the above method were added drop-wise to 1200 grams of dry, 8 meshed,alumina coated TiO₂ prepared according to example 25, which was spreadto a 1-cm thickness on polyethylene film. The pigment was mixed andtransferred to a one gallon wide-mouthed plastic bottle and agitated for10 minutes on a roller mill. The resulting material was steam micronizedto produce the finished pigment.

The finished pigment was incorporated into low-density polyethylene in75% and 50% masterbatches for dispersion and lacing evaluations. Resultsare given in Table 3.

Example 34 Acid Form of Dioctylpyrophosphate

14.54 grams of the acid form of dioctylpyrophosphate prepared accordingto the method described in example 10 were added drop-wise to 1200 gramsof dry, 8 meshed, alumina coated TiO₂ prepared according to example 25,which was spread to a 1-cm thickness on polyethylene film. The pigmentwas mixed and transferred to a one gallon wide-mouthed plastic bottleand agitated for 10 minutes on a roller mill. The resulting material wassteam micronized to produce the finished pigment.

The finished pigment was incorporated into low-density polyethylene in75% and 50% masterbatches for dispersion and lacing evaluations. Resultsare given in Table 3.

Example 35 Potassium Salt of Dihexylpyrophosphate

The potassium salt of the dihexylpyrophosphate was prepared bydissolving portions of the acid form of dihexylpyrophosphate preparedaccording to the method described in example 31 in ethanol whichcontained phenolphthalein. Approximately 0.5M ethanolic KOH solution wasadded dropwise to the solution of dihexylpyrophosphate until thereaction mixture turned slightly pink. The resulting solution was thendried on a rotary evaporator at room temperature. The remaining residuewas used for surface treatment of TiO₂ pigment.

11.17 grams of the potassium salt of dihexylpyrophosphate preparedaccording the above described method was dissolved in 78.0 grams oftetrahydrofuran. The tetrahydrofuran solution of the potassium salt ofdihexylpyrophosphate was added drop-wise to 1200 grams of dry, 8 meshed,alumina coated TiO₂ prepared according to example 25, which was spreadto a 1-cm thickness on polyethylene film. The pigment was mixed andtransferred to a one gallon wide-mouthed plastic bottle and agitated for10 minutes on a roller mill. The resulting material was steam micronizedto produce the finished pigment.

The finished pigment was incorporated into low-density polyethylene in75% and 50% masterbatches for dispersion and lacing evaluations. Resultsare given in Table 3.

Example 36 Acid Form of Pentaoctyltripolyphosphate

The acid form of pentaoctyltripolyphosphate was prepared in accordanceto Alder, Howard and Woodstock, Willard. Chem. Industries, 1942, 51, 516with the following considerations: 17.0 grams of P₂O₅ were added to 26.0grams of 1-octanol with stirring using a stir bar or a mechanicalstirrer. No cooling was employed during the reaction. The temperaturereached as high as ˜125-145° C. during the mixing of the P₂O₅ with thealcohol, and the reaction was considered complete when the temperaturedeclined to room temperature.

10.85 grams of the acid form of pentaoctyltripolyphosphate preparedaccording to the above method were dissolved in 43.9 grams oftetrahydrofuran. The tetrahydrofuran solution ofpentaoctyltripolyphosphate was added drop-wise to 1200 grams of dry, 8meshed, alumina coated TiO₂ prepared according to example 25, which wasspread to a 1-cm thickness on polyethylene film. The pigment was mixedand transferred to a one gallon wide-mouthed plastic bottle and agitatedfor 10 minutes on a roller mill. The resulting material was steammicronized to produce the finished pigment.

The finished pigment was incorporated into a 75% low-densitypolyethylene masterbatch for dispersion evaluation. Results are given inthe Table 3.

Example 37 Acid Form of Pentaoctyltripolyphosphate

13.27 grams of the acid form of pentaoctyltripolyphosphate preparedaccording to the above method were dissolved in 40.2 grams oftetrahydrofuran. The tetrahydrofuran solution ofpentaoctyltripolyphosphate was added drop-wise to 1200 grams of dry, 8meshed, alumina coated TiO₂ prepared according to example 25, which wasspread to a 1-cm thickness on polyethylene film. The pigment was mixedand transferred to a one gallon wide-mouthed plastic bottle and agitatedfor 10 minutes on a roller mill. The resulting material was steammicronized to produce the finished pigment.

The finished pigment was incorporated into a 75% low-densitypolyethylene masterbatch for dispersion evaluation. Results are given inthe Table 3.

Example 38 Acid Form of Trioctyltetrapolyphosphate

The acid form of trioctyltetrapolyphosphate, was prepared in accordanceto Alder, Howard and Woodstock, Willard. Chem. Industries, 1942, 51, 516with the following considerations: 28.4 grams of P₂O₅ were added to 39.0grams of 1-octanol with stirring using a stir bar or a mechanicalstirrer. No cooling was employed during the reaction. The temperaturereached as high as ˜125-145° C. during the mixing of the P₂O₅ with thealcohol, and the reaction was considered complete when the temperaturedeclined to room temperature.

10.80 grams of the acid form of trioctyltetrapolyphosphate preparedaccording to the above method were dissolved in 47.1 grams oftetrahydrofuran. The tetrahydrofuran solution oftrioctyltetrapolyphosphate was added drop-wise to 1200 grams of dry, 8meshed, alumina coated TiO₂ prepared according to example 25, which wasspread to a 1-cm thickness on polyethylene film. The pigment was mixedand transferred to a one gallon wide-mouthed plastic bottle and agitatedfor 10 minutes on a roller mill. The resulting material was steammicronized to produce the finished pigment.

The finished pigment was incorporated into a 75% low-densitypolyethylene masterbatch for dispersion evaluation. Results are given inTable 3.

Example 39 Acid Form of Trioctyltetrapolyphosphate

13.28 grams of the acid form of trioctyltetrapolyphosphate preparedaccording to the method described in example 15 were dissolved in 41.3grams of tetrahydrofuran. The tetrahydrofuran solution oftrioctyltetrapolyphosphate was added drop-wise to 1200 grams of dry, 8meshed, alumina coated TiO₂ prepared according to example 25, which wasspread to a 1-cm thickness on polyethylene film. The pigment was mixedand transferred to a one gallon wide-mouthed plastic bottle and agitatedfor 10 minutes on a roller mill. The resulting material was steammicronized to produce the finished pigment.

The finished pigment was incorporated into a 75% low-densitypolyethylene masterbatch for dispersion evaluation. Results are given inTable 3.

TABLE 3 Dispersion Lacing Example 25 570 1.4 Example 27 840 1.2 Example28 690 1.6 Example 29 550 1.4 Example 30 870 1.7 Example 31 1,570 1.5Example 32 860 1.2 Example 33 230 1.2 Example 34 1,560 1.3 Example 351,760 1.5 Example 36 1,890 not measured Example 37 3,860 not measuredExample 38 2,240 not measured Example 39 4,860 not measured ComparativeExample 3 13,700 1.4

The data in the table illustrate that dispersion performance of TiO₂pigments, treated with the organo acid pyrophosphates and organo acidpolyphosphates, is dramatically improved over like pigmentary basestreated with a conventional, commercially used organic treatment,triethanolamine (comparative Example 3). Further, the excellentdispersion performance is obtained with no significant decay inresistance to lacing. The standard error for the lacing measurement isabout 0.1 to 0.2.

Having thus described and exemplified the invention with a certaindegree of particularity, it should be appreciated that the followingclaims are not to be so limited but are to be afforded a scopecommensurate with the wording of each element of the claim andequivalents thereof.

1. A polymer film comprising: (i) a treated pigment, wherein saidtreated pigment comprises titanium dioxide and an organo-phosphoric acidcompound having the formula:R′_(n)—P_((n−2))O_(4+[3(n−3)]) wherein n=4-14, and each R′ is an organicgroup having from 2 to 22 carbon atoms or hydrogen and within any onemolecule, any two or more R′ groups may be the same provided that atleast one of the R′ groups is not hydrogen; and (ii) a polymer, whereinsaid organo-phosphoric acid compound is present in an amount from about0.01 percent to about 5 percent by weight, based on the weight of thetitanium dioxide, and said treated pigment is present in an amount ofabout 20 wt. % based on the weight of the polymer film.
 2. The polymerfilm of claim 1, wherein said polymer is polyethylene.
 3. The polymerfilm of claim 1, further comprising an additional metal oxide selectedfrom the group consisting of aluminum oxide, silicon dioxide andzirconium oxide.
 4. A polymer film comprising: (i) a treated pigment,wherein said treated pigment comprises titanium dioxide and anorgano-phosphoric acid compound having the formula:R′_(n)—P_((n−2))O_(4+[3(n−3)]) wherein n=4-14, and each R′ is an organicgroup having from 2 to 22 carbon atoms or hydrogen and within any onemolecule, any two or more R′ groups may be the same provided that atleast one of the R′ groups is not hydrogen; and (ii) a polymer, whereinsaid polymer comprises polyethylene, wherein said organo-phosphoric acidcompound is present in an amount from about 0.01 percent to about 5percent by weight, based on the weight of the titanium dioxide, andwherein said treated pigment is present in an amount of about 20 wt. %based on the weight of the polymer film.
 5. A polymer film comprising:(i) a treated pigment, wherein said treated pigment comprises titaniumdioxide and an organometaphosphate compound having the formula:(R″PO₃)_(m) wherein m=1-14, and each R″ is an organic group having from2 to 22 carbon atoms or hydrogen and within any one molecule, any two ormore R″ groups may be the same provided that at least one of the R″groups is not hydrogen; and (ii) a polymer, wherein saidorganometaphosphate compound is present in an amount from about 0.01percent to about 5 percent by weight, based on the weight of thetitanium dioxide, and said treated pigment is present in an amount ofabout 20 wt. % based on the weight of the polymer film.
 6. The polymerfilm of claim 5, wherein said polymer is polyethylene.
 7. The polymerfilm of claim 5, further comprising an additional metal oxide selectedfrom the group consisting of aluminum oxide, silicon dioxide andzirconium oxide.
 8. A polymer film comprising: (i) a treated pigment,wherein said treated pigment comprises titanium dioxide and anorganometaphosphate compound having the formula:(R″PO₃)_(m) wherein m=1-14, and each R″ is an organic group having from2 to 22 carbon atoms or hydrogen and within any one molecule, any two ormore R″ groups may be the same provided that at least one of the R′groups is not hydrogen; and (ii) a polymer, wherein said polymercomprises polyethylene, wherein said organometaphosphate compound ispresent in an amount from about 0.01 percent to about 5 percent byweight, based on the weight of the titanium dioxide, and wherein saidtreated pigment is present in an amount of about 20 wt. % based on theweight of the polymer film.